The brief of an amicus curiae may be filed only by leave of the Commission or the Judge. The brief may be conditionally filed with the motion for leave conforming to § 2200.40. A motion for leave shall identify the interest of the applicant and shall state the reasons why a brief of an amicus curiae is desirable. Any amicus curiae shall file its brief within the time allowed the party whose position the amicus will support unless the Commission or the Judge, for good cause shown, grants leave for later filing. In that event, the Commission or the Judge may specify within what period an opposing party may answer. The brief of an amicus curiae shall conform to § 2200.74 or § 2200.93.